<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
var i=parseInt(prompt("请输入您的成绩"));
if(i>=90){
    alert("优秀");
}else if(i>=80){
    alert("良好");
}else if(i>=60){
    alert("及格");
}else{
    alert("不及格");
}

</script>
</body>
</html>